Question 109162
Let t=number of hours that elapses 'till the two trains are 550 km apart
Distance(d)=Rate(r) times Time(t) or d=rt; r=d/t and t=d/r

The easy way to approach this problem is to recognize that the two trains are separating at the rate of 62 km/h+48 km/h or 110 km/h.  So our equation to solve is:

550=110t  divide both sides by 110
t=5 hours

CK

5*62+5*48=550
310+240=550

550=550

Hope this helps----ptaylor